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Old 09-09-1999, 03:15 PM
akry's Avatar
W140 Maniac
Join Date: May 1999
Location: Burnaby, BC, Canada
Posts: 960
To Lee and All,

My '92 400SE runs at about 87-90 degree without A/C and 97-100 degree with A/C on(all during the night, outside temp. 18C). How about other MBs??

My car used to run cooler than now(about 85 degree with A/C during a 33 degree summer day). Is it because of engine wear?? Or the tuning of the engine when the car is serviced(of my knowledge is that MB has changed the engine management computer in late 1994 to get better fuel economic/emission,).

Happy Motoring....
Andy Kuo
'92 400SE
70,990 KM
Old 09-09-1999, 04:13 PM
Posts: n/a
My 500E normally runs about 90, but can run up higher if I'm pushing it hard. I've seen it hit about 110.

You mentioned tuning might have an effect on temp and I'm curious about this. I know that with my older cars, a few degrees retard could make a big drop in temp (especially if the timing was advanced to the point of detonation. Also a slightly richer fuel mixture helped bring temp. down. In this case would a performance chip help?

Benzmac and others what do you say? Inquiring minds want to know!

Old 09-09-1999, 05:37 PM
akry's Avatar
W140 Maniac
Join Date: May 1999
Location: Burnaby, BC, Canada
Posts: 960
To Eric,

Yes, my 400SE now runs up to 115 on a hot day with A/C on. But it never runs this hot when I bought the car new. The temp. gets hotter when the W140 was facelifted/new engine management(late 1994 as 1995 model).

Since you have 500E, it may have the same engine management as 500SEL. What if the car with DOHC V8s(pre-1994) are tuned with late-1994+ spec??? Is there difference in tuning?? Lee, and all alcknowdgable ppl, please tell me, thank you....

Happy Motoring....
Andy Kuo
'92 400SE
70,995 KM
Old 09-09-1999, 09:23 PM
Registered User
Join Date: Mar 1999
Location: Suwanee, GA, USA
Posts: 4,712
This is a good thought. I have some info though to the contrary on the tuning/temp. issue. I know Lee's car runs 100-110 all of the time. It is a 92, Now Beth's '94 E420 runs at 80-90 all of the time. I think that there is something going on we are all missing. What it is I don't know. If we figure it out we rule though!

1987 16V

Old 09-09-1999, 10:41 PM
Registered User
Join Date: Aug 1999
Location: Florida / N.H.
Posts: 8,768

Running temps are also affected by coolant
mixture percentages. A rich mix [ over 50%
anti-freeze] will run hotter than a mild mix.
This can be considered when comparing temps on same models.
Straight h20 takes heat away best and
straight anti-freeze the least. A 50/50
mix is recommended.
Old 09-10-1999, 12:42 AM
Chris Ecklund
Posts: n/a
Here is my most educated from the cracker-jack box responce...

My 94 Jeep Cherokee started to run hotter as it got older, and here is my most educated guess's as why this is happening.

1. As antifreeze gets older its chemical ability to dissapate heat is reduced along with its freezing ability.(coming from Canada trust me on this one)

2. As the rad hoses get older they may become encrusted on the insides with gunk.

3. As the thermostat gets older, the wax and spring do not respond as good as they did when new, meaning it will (may) not open as well as it did when it was new.

4. The impellar on the waterpump slowly wears out, and the coolant mixture will not get forced through as much. ( like lower the amperage in electrical paths).

5. Look at the rad from the inside, is it full of junk and debris?. As the passages get full of rust and other junk, so goes its ability to shed heat.

6. How about the cooling fins?. Is there bugs and junk covering them up?, if so clean the rad from the inside-out, meaning get your hose and spray the water from the inside of the engine compartment to the rad, forcing the junk back to the front bumper.

Some of these are more important and a higher percentage than others but it is usually a slow combination of all of them acting together that does it.

The best analogy is to draw a parallel to your blood vessels clogging up with bad cholestrohol(sp), it happens slowly over a period of time, until your blood pressure is to high. A maybe somewhat crude explanation, but I am sure you get the point.

And thats my 2 cents worth....

which being 2 cents Canadian means very little...

Chris Ecklund
98 300 DT
Old 09-10-1999, 01:01 AM
JCE's Avatar
JCE JCE is offline
Down to the Wear Bars
Join Date: May 1999
Location: So Kalifornia
Posts: 2,189
When I took over the care of my dad's 87 300E, I took it to my mechanic for update on any maintenance neglect. He found no records of the coolant having been changed in 6 years! The water pump was starting to leak, and the hoses were bad. He replaced the coolant, thermostat, plastic 'stat cover and hoses immediately, and a week later replaced the coolant again when he did the water pump. The temp always ran in the high 90's before the changes, and now routinely runs in the low 80s.

87 300E 53,000 miles
Shadow Silver
Old 09-10-1999, 09:31 PM
akry's Avatar
W140 Maniac
Join Date: May 1999
Location: Burnaby, BC, Canada
Posts: 960
To Benzmac,

Regarding the 1994 E420, is it late 1994 model or early?? I believe E420s also have the management changed. Correct me if I am wrong....

I have my car serviced only at Mercedes Dealers, and have Mercedes do what they have to do. That's why I suspect that the problem is with the tuning. Since late-1994+ have different managements, maybe it will have different tuning specs, too.

P.S. I have coolant(50/50 as factory recommended) changed every 2 year and oil changed every 3000 KM or every season changes(summer-winter, winter-summer).

Happy Motoring....
Andy Kuo
'92 400SE
71,014 KM

[This message has been edited by akry (edited 09-10-1999).]
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